1. Field of the Invention
The present invention relates to optic antennas, optics lenses, and the positioning of electromagnetic readers and writers. More particularly, it relates to the use of microlayered optical lenses and shaped surfaces, a portion of which contains a continuously varied surface, coupled with an amplifying grating antenna as an optical head to create a localized optical spot of desired polarization, at a desired distance with a maximum peak in intensity.
2. Background Information
The storage of information in magnetized medium often is limited by the spot size of light intensity focused at the desired storage location. The intensity loosens the polarization of the medium so that a logical/analog bit may be stored. The smaller the spot size the smaller the storage space required for a bit, thus, the more information that can be stored on the medium.
To obtain a localized spot, current systems illuminate an antenna, which reradiates the light, forming various patterns some of which contain parts that are localized with a reasonable intensity to be used for storing/reading logical/analog bits in a medium. Spot sizes smaller than the illuminating wavelength (λ) can be achieved by antennas composed of multiple conductive elements, separated by a gap whose lateral dimension is much smaller than λ, positioned in the path of the incident illumination.
An example of a conventional system is the antenna system of Grober et al. (U.S. Pat. No. 5,696,372). FIGS. 1 and 2 show the Grober antenna, comprised of two antenna arms 16 and 18, with a gap 24 of transverse dimension “d” separating terminations 20 and 22 of conductive arms 16 and 18 respectively. The incident illumination forms an initial spot size 26 on a target medium 30. When the antenna is placed in the illumination path the incident illumination on the antenna arms 16 and 18 results in induced currents in the conductors (16 and 18). The induced currents result in charge accumulation at the terminals 20 and 22 and thus a resultant displacement current is created between the terminals. The displacement current causes re-radiation similar to that caused by a dipole of dimension “d” forming a spot size of similar dimension on the target medium 30.
To read information the gap 24 is placed close to the target medium 30 to be queried. Fluctuations in the near field 43 of the gap 24 produced by illumination of the target medium 30 (e.g., off-axis illumination, illumination from beneath the target medium 30, self induced emanations, etc . . . ) results in induced currents in the conductive arms 16 and 18 which, as described above, cause reradiated illumination. The reradiated illumination can be directed up (away from the target medium 30) through the optics to be read.
A disadvantage of multiple solid antennas is that the re-radiated field becomes depolarized during the superposition process resulting in lower than desired maximum peak in the irradiated field and a larger than desired spot size at the desired distance from the antenna.
Hence a system/device/method, which can create a smaller spot size, while maintaining the polarization, can enable the storage and reading of larger amounts of data.
The read and write functions take place in the near field region. In addition to decreased illumination spot sizes, placement of the antenna relative to the target medium is important. Several mechanisms have been developed to sweep the reading and writing system over the target medium. FIG. 6 shows a conventional system, 600, for channeling a focused optical beam 660 onto a localized spot (760 in FIG. 7). The device is a layer of silicon 610 upon which several layers of metal are deposited 620 and 630. Underneath one of the layers is deposited a waveguide 640 containing either a hole or a different index of refraction material 650. The device is turned on its side and used to channel/guide an optical beam 660 to a desired spot on a recording media.
FIG. 7 shows the use of the device described above as shown in FIG. 6 in a read/write device 700 for use in a rotating magnetic or optical storage and retrieval system. An optical beam illumination 710 is focused onto the entrance of the waveguide structure 740 by a condensing lens 720, which condenses the initial illumination 710 into a condensed illumination 730. The internally reflected beam travels through the waveguide exiting as guided illumination 750, illuminating the target medium 770 at an illumination spot 760. Typical disadvantages of devices similar to that described are the size of the components; that the component parts must be accurately attached to each other; and the spot sizes are 200 nm or greater, which becomes the limiting factor of the recordable medium's storage space. The need to assemble diverse components also substantially increased cost.
A delivery system that can maintain the optimum spacing between the read/write system and the target material aids to increase storage rates by providing stable conditions by which to estimate the amount of time needed to store a logical/analog polarization value.
Therefore an integrated delivery system, providing optimum spacing between the target medium and the read/write head alone or in conjunction with a system/device/method that can create a smaller spot size, while maintaining the polarization, can enable the storage and reading of larger amounts of data in a cheaper and more reliable fashion than previous systems.